Treatment of non-insulin-dependent diabetes mellitus and its complications. A state of the art review

Management of type 2 diabetes mellitus in the elderly: special considerations

The principles of managing type 2 diabetes mellitus in the elderly are no different from those in younger patients, but the priorities and therapeutic strategies need to be cautiously individualised. The objectives of treatment are to improve glycaemic control in a stepwise approach that involves nonpharmacological methods including diet and exercise, and pharmacological therapy including mixtures of oral antihyperglycaemic agents alone or in combination with insulin. Although the goals of treatment may be the same for elderly and younger patients, certain aspects of type 2 diabetes in the elderly require special consideration. Treatment decisions are influenced by age and life expectancy, comorbid conditions and severity of the vascular complications. Adherence to dietary therapy, physical activity, and medication regimens may be compromised by comorbid conditions and psychosocial limitations. Drug-induced hypoglycaemia has been the main consideration and the most serious potential complication. In addition, the long term macrovascular and microvascular complications of type 2 diabetes are a source of significant morbidity and mortality. Indeed, vascular and neuropathic complications are already present at the time of diagnosis in a significant number of patients, and the impact of improved diabetes control depends on the age and life expectancy of the patient. Age-related changes in pharmacokinetics and the potential for adverse effects and drug interactions should also be considered when choosing appropriate pharmacological therapy. In general, a conservative and stepwise approach to the treatment of the elderly patient with type 2 diabetes is suggested; treatment may be initiated with monotherapy, followed by early intervention with a combination of oral agents including a sulphonylurea as a foundation insulin secretagogue in addition to a supplemental insulin sensitiser. Insulin therapy is eventually required if significant hyperglycaemia [glycosylated haemoglobin (HbA1c) >8%] persists despite oral combination therapy. Combination therapy with evening insulin and a long-acting sulphonylurea such as glimepiride is an effective strategy to improve hyperglycaemia in the elderly patient with type 2 diabetes in whom polypharmacy with oral agents is unsuccessful. In addition, such a regimen is simple to follow for the patient who may not be able to adhere to a more complicated insulin regimen. Hyperglycaemia in the elderly can be managed well with practical intervention and a straightforward treatment plan to enhance compliance. Optimal glycaemic control should be possible for every patient if treatment is individualised; however, strict glycaemic control may not be achievable in all patients or even desirable in many elderly patients.

Effects of dietary restriction on insulin resistance in obese mice

In many cases, development of insulin resistance has been linked to obesity and may contribute to mechanism of aging. The role of diet, irrespective of degree of obesity, in modulating insulin resistance and development of age degeneration disease remains uncertain. Lowered blood glucose levels are commonly associated with diet restriction (DR), which is an intervention shown to successfully retard aging and age associated disease. The effects of DR on blood glucose and insulin resistance were measured in yellow obese (A(vy)/A), lean black (a/a) mice and in another common inbred strain (B6C3F1) (at three different ages). The yellow obese mice become diabetic as a result of an insulin receptor defect which is not clearly understood. Insulin responses and radioinsulin binding were assayed in yellow obese and lean black mice fed either ad libitum (AL) or DR diets (YAL, BAL, YDR and YAL, respectively) at four different circadian intervals. The B6C3F1 controls were fed either AL (CAL) or DR (CDR) and measures were made at six circadian stages and three different ages. Within 23 days, DR produced a significant loss in body weight and a time-dependent 22-55% reduction in basal blood glucose levels in the yellow obese mice. Additionally, exogenous insulin produced circadian stage dependent (at the time of food intake) reductions in blood glucose in the YDR animals that were not present in YAL animals. (125)I-Insulin binding in liver was increased nearly 2-fold in YDR and BDR mice during the time of day that animals were active and eating. (125)I-Insulin binding was two-fold-higher in CDR mice at 4, 12 and >24 months of age. Binding decreased as a function of age in both the CAL and CDR animals. However, even in the >24 month group the CDR animals were found to have levels of binding that were as high as those found in younger CAL liver. The mechanism of action appears to be through resolution of insulin resistance by modulating an insulin receptor defect.

Obesidade: atualização sobre sua etiologia, morbidade e tratamento

As tendências de transição nutricional ocorridas neste século direcionam para uma dieta mais ocidentalizada, a qual, aliada à diminuição progressiva da atividade física, converge para o aumento no número de casos de obesidade em todo o mundo. Isso representa aumento na morbidade e na mortalidade associadas à obesidade, já que esta é fator de risco para várias doenças como diabetes tipo II, hipertensão, doenças cardiovasculares e cálculo na vesícula biliar. A obesidade se apresenta não apenas como problema científico e de saúde pública, porém como grande indústria que envolve o desenvolvimento de fármacos, de alimentos modificados e estratégias governamentais estimulando a prática regular de atividade física e a orientação alimentar a fim de promover melhores hábitos. Assim, o conhecimento das causas e estratégias preventivas da obesidade é o objeto de estudo de pesquisadores de diferentes centros. Esse artigo tem como objetivo rever esses estudos, abordando o aumento na prevalência e incidência da obesidade, doenças relacionadas ao excesso de peso e os tratamentos para redução da gordura corporal.

ATP-dependent desensitization of insulin binding and tyrosine kinase activity of the insulin receptor kinase. The role of endosomal acidification

Incubating endosomes with ATP decreased binding of 125I-insulin but not 125I-labeled human growth hormone. Increasing ATP concentrations from 0.1 to 1 mM increased beta-subunit tyrosine phosphorylation and insulin receptor kinase (IRK) activity assayed after partial purification. At higher (5 mM) ATP concentrations beta-subunit tyrosine phosphorylation and IRK activity were markedly decreased. This was not observed with nonhydrolyzable analogs of ATP, nor with plasma membrane IRK, nor with endosomal epidermal growth factor receptor kinase autophosphorylation. The inhibition of endosomal IRK tyrosine phosphorylation and activity was completely reversed by bafilomycin A1, indicating a role for endosomal proton pump(s). The inhibition of IRK was not due to serine/threonine phosphorylation nor was it influenced by the inhibition of phosphotyrosyl phosphatase using bisperoxo(1,10-phenanthroline)oxovanadate anion. Prior phosphorylation of the beta-subunit with 1 mM ATP did not prevent the inhibition of IRK activity on incubating with 5 mM ATP. To evaluate conformational change we incubated endosomes with dithiothreitol (DTT) followed by SDS-polyacrylamide gel electrophoresis under nonreducing conditions. Without DTT the predominant species of IRK observed was alpha2 beta2. With DTT the alpha beta dimer predominated but on co-incubation with 5 mM ATP the alpha2 beta2 form predominated. Thus, ATP-dependent endosomal acidification contributes to the termination of transmembrane signaling by, among other processes, effecting a deactivating conformational change of the IRK.

Treatment of type 2 diabetes mellitus

Although most patients with type 2 diabetes mellitus can be initially managed with diet and exercise alone, most eventually require at least oral agents if not insulin to maintain glycemic control. Appropriate therapeutic regimens may be difficult to design, given the diversity of drugs available for clinical use. Physicians must consider not only glycemic control, but also patient preference, concomitant medical conditions, and cost when designing therapeutic regimens.

Diabetic retinopathy

Diabetic retinopathy is the commonest cause of blindness amongst individuals of working age. The onset of retinopathy is variable. Regular ophthalmic screening is essential in order to detect treatable lesions early. Retinal laser therapy is highly effective in slowing the progression of retinopathy and in preventing blindness. As the sufferers of diabetes mellitus, the commonest endocrine disorder, now constitute approximately 1-2% of Western populations, concerted multidisciplinary effort must be made towards cost-effective community screening by the medical community.

Diabetes mellitus in older patients. Is tight blood glucose control warranted?

Diabetes mellitus is a major health problem in the older population, where it is mainly of the non-insulin-dependent type [i.e. non-insulin-dependent diabetes mellitus (NIDDM)]. Epidemiological evidence and extrapolation of trial data from patients with insulin-dependent diabetes mellitus (IDDM) suggests that improving glycaemic control reduces the risk of developing microvascular complications (i.e. retinopathy, nephropathy and neuropathy) and also slows the rate of progression of these complications in patients with early disease. Macrovascular morbidity and mortality is, however, more common than microvascular disease in the older population and the evidence that improved glycaemic control significantly reduces the impact of macrovascular disease is weak. Thus, the overall benefits of tight glycaemic control are less well defined in older patients, who tend to have NIDDM, than in younger patients with IDDM. There are small but significant risks associated with tight glycaemic control in the older patient, including potentially fatal hypoglycaemia with sulphonyl-ureas and/or insulin, and fatal metformin-induced lactic acidosis. Patients at especially high risk of these complications can, however, be identified and inappropriate pharmacological intervention can be avoided.

Antidiabetic plants and their active constituents

Diabetes mellitus is a debilitating and often life-threatening disease with increasing incidence in rural populations throughout the world. A scientific investigation of traditional herbal remedies for diabetes may provide valuable leads for the development of alternative drugs and therapeutic strategies. Alternatives are clearly needed because of the inability of current therapies to control all of the pathological aspects of diabetes, and the high cost and poor availability of current therapies for many rural populations, particularly in developing countries. This review provides information on more than 1200 species of plants reported to have been used to treat diabetes and/or investigated for antidiabetic activity, with a detailed review of representative plants and some of great diversity of plant constituents with hypoglycemic activity, their mechanisms of action, methods for the bioassay of hypoglycemic agents, potential toxicity problems, and promising directions for future research on antidiabetic plants. The objective of this work is to provide a starting point for programs leading to the development of indigenous botanical resources as inexpensive sources for standardized crude or purified antidiabetic drugs, and for the discovery of lead compounds for novel hypoglycemic drug development.